1. Field of the Invention
The present invention relates to an apparatus for detecting a pattern of crest lines, which apparatus is used in discriminating, for example, a dactylogram having an individual pattern of crest lines.
2. Description of the Related Art
Various apparatuses for discriminating a pattern of crest lines which is a stripe pattern consisting of a plurality of crest lines, such as a dactylogram, have been proposed. For example, an apparatus for detecting a stripe pattern is disclosed in Japanese Examined Patent Publication (Kokoku) No. 59-27945. According to the invention disclosed in the above publication, one picture element is first arbitrarily selected, which element is one of a plurality of minimum unit picture elements by which a picture image of a stripe pattern is constructed. Next, the degree of shading of each picture element is detected by a turn in one direction, which is one of a group of predetermined radial directions having the above-mentioned selected picture element as a center, and the absolute values of a shading difference between adjacent picture elements are accumulated. The same process as above-mentioned is repeated in other directions, and the direction which corresponds to the extremity of a group of the before-mentioned accumulated value, which value corresponds to each direction, is determined to be the direction of a line element of a crest line in the selected picture element. The same process as before-mentioned is repeated for each of the other picture elements.
Nevertheless, in the above-mentioned detecting system, a problem arises in that the direction of a crest line cannot be detected, or cannot be easily detected, if the crest line is cut off, crushed, or branched off, on the way thereof, such as a picture image of a dactylogram.